1. Field of the Invention
The present invention relates to an optical sensor for detecting the pulse wave of a human body.
2. Related Art
JP-A-11-70087 proposes a wristwatch-type device for detecting the pulse wave of a human body. This detecting device is worn on the user""s wrist. The device includes a detecting element for detecting a pulse wave and a sensor body including a display. The detecting element is fixed on the front side of the user""s wrist corresponding to the palm of the user""s hand by a band attached to the sensor body. The information of pulse wave detected by the detecting element is displayed on the display of the sensor body fixed on the back side of the user""s wrist.
The two bones (the radius and the ulna) pass through the front side of the user""s wrist. Therefore the detecting element has a tendency to slip off the detection position of the user""s wrist, since the skin surface of the front side of the user""s wrist greatly moves as the user""s wrist moves. Furthermore, the user feels uncomfortable since the radius and the ulna are pressed. As a result, the user further moves his/her wrist unconsciously and it becomes further difficult to detect the pulse wave stably.
The present invention overcomes the above drawbacks, and has an object to provide a human pulse wave sensor which is capable of detecting the pulse wave of a human body stably and has high detection probability.
The pulse wave sensor according to the present invention includes a detecting element and a sensor body. The pulse wave sensor is worn on the back side of the user""s wrist corresponding to the back of the user""s hand for detecting the pulse wave of the user. The detecting element includes a light emitting element and a light receiving element. The sensor body is connected to the detecting element by a signal line.
Preferably, a translucent member is arranged on the light emitting element and the light receiving element. The translucent member has a convex surface. The detecting element is attached on the back side of the user""s wrist by a dedicated belt so that the convex surface of the translucent member is in intimate contact with the surface of the user""s skin. The light emitting element and the light receiving element are arranged in the longitudinal direction of the user""s arm. The sensor body is attached on the back side of the user""s wrist by a dedicated belt other than the belt of the detecting element so that it is arranged on the detecting element. A cushion is arranged between the sensor body and the detecting element.
According to this construction, the user does not feel uncomfortable when the pulse wave sensor is worn on the user""s wrist. Furthermore the detecting element is fixed on the user""s wrist without slipping off the detection position of the user""s wrist, even if the user is in motion. Accordingly the pulse wave sensor can stably detect the pulse wave of the user.